Instruments for examination and therapy of the esophagus and colon, or "endoscopes," as well as those used for abdominal, chest and intracranial procedures, such as "laparoscopes" typically employ a passage in a flexible hose or conduit which is inserted into the patient from the mouth or anus or surgically prepared opening. The distal end of the endoscope or laparoscope can be steered or pointed by means of manual controls mounted at the proximal end of the instrument. Typically, the first few inches of the distal end can be flexed 90.degree. or more in any direction with respect to the body of the device by pulling on one or more cables running inside the instrument. Typically, a set of hand-operated knobs actuating a rack and pinion drive cause the desired cable or cables to be pulled, resulting in curvature of the distal end of the instrument. By this means, viewing devices connected to the distal end of the instrument, be they fiberoptic or miniature television, can be pointed toward point of interest, and the forward motion of the device can be approximately directed as the instrument is pushed into the patient. In addition, the trained endoscopist can employ the flexed distal end to temporarily distort the natural curve of the gut, typically in colonoscopy at the sigmoid, by hooking the instrument over a curve in the gut wall and pulling on it. This maneuver tends to straighten the gut so that further insertion of the endoscope is possible.
Present endoscopic and laparoscopic instruments offer limited working length, require great skill, encounter difficulty in maneuvering, and produce high internal forces against tissues. Moving the devices around a bend exerts a force on the tissues at that bend, and the strength of the tissue thus limits advancing the instrument around compound bends. Present instruments for urethral and laparoscopic applications, in particular, have little or no flexibility. Due to the stiffness of the present generation proctoscopes, manual controls do not provide adequate "feel" of the environment at the tip of the scope to the user. Such devices are thus steered by visual rules only, when a combination of visualization and tactile sensing could provide enhanced utility.
Throughout the maneuvers of the endoscope or laparoscope the gut or other distortable or distendable walls through which the device is being inserted often tend to resist movement and slip over the instrument, suddenly leaving the working end of any optical devices in a viewing position that is quite different from that which was observed just previously. Additionally, these semi-flexible instruments are used to guide specimen sampling devices to specific locations for tissue or sample retrieval.
Another common endoscopic procedure for which such instruments are used includes cauterization and polyp removal. In the case where a sample specimen is being gathered or where a snare is being used to catch and remove a polyp, the uncertainty of the location of the end of the scope and the surrounding walls of the gut creates a situation in which the operator of the device must engage in active and often protracted pursuit of the target. While this procedure is taking place, air or saline is typically injected to distend the gut to allow visibility of the target and surrounding tissue. Thus, along with the need to control air, saline, and tracking of moving targets in a breathing, flexing environment, endoscopic and laparoscopic procedures frequently require more than two hands, making an additional assistant necessary. In some instances this additional assistant may also be provided with a viewing port or in the case of the TV display may be watching the same screen as the endoscopist and laparoscopist.
Endoscopes apply pressure to the walls of the gut, especially when inserted to lengths of 50 cm or more, since some portion of the instrument will be following a relatively sharp curve around an angle of at least 90 degrees. In these conditions, any forward or backward motion of the endoscope will necessarily cause pressure to be exerted on the gut walls at these points. This tendency is compounded by the necessity to build instruments which are stiff enough to avoid buckling/bending when inserted against resisting forces in the gut. The gut often reacts to the presence of an endoscope by contracting radially, constricting its passage. The use of endoscopes in the gut is further impeded by the necessity of passing through the narrow portion of the sigmoid and several curves totalling more than 540 degrees. Attempts at forward (or backward) motions of the endoscope can result in relatively large and potentially dangerous forces being applied to the walls of the gut at its points of contact with the conduit. It has been noted that even the best endoscopists cannot always reach the cecum (end of the large intestine at the appendix) due to cramping of the gut, the inability to control the position of the endoscope along its entire length, and the danger of applying forces which might herniate or rupture the gut. The problem is further compounded by the fact that frequently the gut being inspected endoscopically is more fragile than a healthy gut, and thus least able to withstand the trauma of intrusive endoscopic procedures.
There is a real need in the art of endoscopic examination for a more flexible instrument that can avoid all or most of the above-described problems, yet still achieve the objectives of safe, reliable and efficient exploratory procedures.
It would be useful to provide an exploratory device which could be advanced through the gut, esophagus, surgically prepared opening or other cavity having compressible walls, without exerting undue force on these walls at any point, yet maintaining an effective degree of flexural control.
It would also be useful to provide an exploratory device which would be capable of reacting to motions occurring in the walls of the cavity being studied, such as a moving, living gut, by offering little resistance to such motions.
Furthermore, an advance in the art could be realized if there existed an exploratory instrument which, though flexible, could be stiffened along its entire length, providing a stable platform for the deployment of exploratory instruments, such as medical devices for performing visual or therapeutic procedures in, for example, laparoscope, urethral and proctological applications.
It would be useful, in addition, to provide an exploratory instrument which could be maintained in a relatively motionless position with respect to a target point on the wall of a moving subject, such as the gut.